Txv Question - http://www.hvacmechanic.com/ Forums
Original message
| carlb7
 |  "Txv Question"
, posted Wed 12 Nov 09:17  
I had a restriction in the line last year and it was determined to be the inside txv in the air handler. I have since educated myself in regards to heat pumps and how they operate. The question I have is there a possibility that I only have one txv inside but not one outside at the compressor? I can not see one there. I know what to look for and am wondering if this system just has one. If so would it be smart to have the outside valve added? I have a Ruud 14 Achiever and it is 4 years old. It does have a large evaporator just before the compressor as well. I noticed that the air temp drops at the handler about 6 degrees and then slowly recovers, could there be a relationship between the txv and this drop. When I hold the small refrig line at the handler it starts warm gets somewhat cold and the warms up again. Any info on this would be much appreciated.
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Replies:
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| bama 101
| "Re(1):Txv Question" , posted Wed 12 Nov 09:38
had a restriction(so you have changed it already)
yes it will have another metering device but is most likely a fixed bore or sometimes called an orfice which can be found in a brass coupling in small line just before entering the outdoor coil,
THERE ARE two types of metering devices commonly found in fixed bore, and expasion valves
Help is just a question away.
Safety is up to you....
....THINK........
....Safety........
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| | carlb7
| "Re(2):Txv Question" , posted Wed 12 Nov 09:55
Would this explain the temperature drop of 6 degrees after about a minute after startup? The small refrigerant line starts warm gets cold and gets warm again during this time.
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| | bama 101
| "Re(3):Txv Question" , posted Wed 12 Nov 09:58
yes if the txv is not been changed,or it is under charged with freon
Help is just a question away.
Safety is up to you....
....THINK........
....Safety........
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| | carlb7
| "Re(4):Txv Question" , posted Wed 12 Nov 10:16
The txv was supposedly changed in the air handler. So this temperature drop is not normal I take it. What would you suggest is the next thing I should do.
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| | Jojo98
| "Re(5):Txv Question" , posted Wed 12 Nov 12:26
The supply air temp. should be room temp. immediatly at start-up if there is no fan time delay, and should quickly heat up. The smaller of the two refrig. lines (liquid line) going to the AHU in heat pump mode should be somewhat warm, and the larger one (discharge line) going to the AHU in heat pump mode should be hot.
What is the supply air temp, return air temp., unit refrigerant pressures. This is what is going to answer your questions.
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| | carlb7
| "Re(6):Txv Question" , posted Wed 12 Nov 13:10
I plan on having a tech come out and check it. A few weeks ago a tech came out to check everything as a preventative and he said all was well. I just have a feeling that my system is not running efficiently. The liquid line starts warm then in a minutes time you can hear what sounds like a vibration and the liquid line becomes cool. Then the temperature starts rebounding slowly to what it first was and the liquid line warms up as well. For instance, unit comes on to 95 degrees, one minute passes, liquid line grows colder, temp from handler drops 6 to 7 degrees, vibration noise goes away, temp starts increasing a degree each minute, temp reaches 95 degrees again, temp continues to increase depending on outside temp. This doesn't sound right.
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